Ventilatory threshold may be a more specific measure of aerobic capacity than peak oxygen consumption rate in persons with stroke

<p>Background: After stroke, aerobic deconditioning can have a profound impact on daily activities. This is usually measured by the peak oxygen consumption rate achieved during exercise testing (VO2-peak). However, VO2-peak may be distorted by motor function. The oxygen uptake efficiency slope (OUES) and VO2 at the ventilatory threshold (VO2-VT) could more specifically assess aerobic capacity after stroke, but this has not been tested.</p> <p>Objectives: To assess the differential influence of motor function on three measures of aerobic capacity (VO2-peak, OUES, and VO2-VT) and to evaluate the inter-rater reliability of VO2-VT determination post-stroke.</p> <p>Methods: Among 59 persons with chronic stroke, cross-sectional correlations with motor function (comfortable gait speed [CGS] and lower extremity Fugl-Meyer [LEFM]) were compared between the different aerobic capacity measures, after adjustment for covariates, in order to isolate any distorting effect of motor function. Reliability of VO2-VT determination between three raters was assessed with intra-class correlation (ICC).</p> <p>Results: CGS was moderately correlated with VO2-peak (<i>r</i> = 0.52, <i>p</i> < 0.0001) and weakly correlated with OUES (<i>r</i> = 0.41, <i>p</i> = 0.002) and VO2-VT (<i>r</i> = 0.37, <i>p</i> = 0.01). LEFM was weakly correlated with VO2-peak (<i>r</i> = 0.26, <i>p</i> = 0.055) and very weakly correlated with OUES (<i>r</i> = 0.19, <i>p</i> = 0.17) and VO2-VT (<i>r</i> = 0.14, <i>p</i> = 0.31). Compared to VO2-peak, VO2-VT was significantly less correlated with CGS (<i>r</i> difference = −0.16, <i>p</i> = 0.02). Inter-rater reliability of VO2-VT determination was high (ICC: 0.93, 95% CI: 0.89–0.96).</p> <p><b>Conclusions:</b> Motor dysfunction appears to artificially lower measured aerobic capacity. VO2-VT seemed to be less distorted than VO2-peak and had good inter-rater reliability, so it may provide more specific assessment of aerobic capacity post-stroke.